You can use your iPhone (or even your Apple Watch!) as a remote for your Apple TV. It’s a convenient feature when you’ve lost the remote in the couch cushions — the Siri Remote really ought to have a built-in AirTag, right?
Even if your remote’s not gone missing, sometimes it’s sitting on the table way over there and you don’t want to interrupt a show by asking for someone to pass it to you. Or maybe, someone is intentionally hogging the remote and you want to pause the video yourself. Either way, it’s really easy to do from an iPhone or an Apple Watch.